Ketone body production and disposal: effects of fasting, diabetes, and exercise

This review describes ketone body kinetics during fasting, diabetes and exercise. During progressive fasting in normal subjects, ketone body production and concentration rise markedly early and begin to plateau after about 5 days, and a reduced metabolic clearance rate, reflecting saturation of muscular ketone uptake, contributes to the hyperketonemia. Under physiologic conditions urinary excretion is always below 10 percent of total turnover. Insulin-deprived type I diabetic patients and controls with fasting ketosis had comparable ketone kinetics and identical maximal removal capacity, and in the overnight-fasted state, 2 hours of moderate exercise at 50 percent VO2 max stimulated muscle ketone extraction. The abstract is truncated, so only this portion is summarized.